I'm trying to install a few packages that allows meshlium to report data in Microsoft SQL Server 2008 R2, but looks like the repositories isn't update because the version of debian is lenny; my question is:

Can I modify the sources.list into debian to access this packages in a newer version of this OS or what is the best practice for do this?

I'm working with Lorena in the problem above, really I know we can't use apt-get to install new packages, but I don´t know if we can use dpkg -i <package> to install. I already download all the packages we need so only remains installed in the system and considering that we have no backup system, we want to make sure that we will not corrupt Meshlium.